Electric current rectifying device



June 19, 1934.

ELECTRIC CURRENT RECTIFYING DEVICE Filed May 22. 1929 10 L AW] *1 Inventor ,Oskar Seitz Attorney Patented June 19, 1934 1,963,819 ELECTRIC CURRENT ascr rrlnc DEVICE Oskar Seitz, Baden, Switzerland, assignor to Aktiengesellschaft Brown Boveri' & Cie, Baden, Switzerland, a joint-stock company of Switzerland Application May 22, 1929, Serial No. 36 L988 In Germany June 4, 1928 2 Claims. (01250-215 This invention relates to improvements in electric current rectifying apparatus of the mercury vapor type and, more particularly, to means for decreasing the vapor density in the operating 5 chamber of such apparatus.

In metallic vapor electric current rectifying apparatus, the action of the electric are on the metallic cathode, which is usually mercury, vaporizes a substantial portion of the mercury 10 thereby creating such vapor density in the operating space of the rectifier as is likely to cause cathode spots on the anodes. Such spots permit a flow of reverse current or backfires through the rectifier with the attendant disturbances of con nected systems and the danger of destruction of the rectifier itself.

Various methods and means have been proposed to reduce the vapor density in the operating space of metaflic vapor rectifiers and, there- 29 by, to decrease the danger of backfiring. One

such method was the provision of an outward extension of the rectifier chamber which extension was commonly called a condensation dome and was arranged to receive and to condense mercury vapor arising from the cathode by contact with the cooled walls thereof. Cooling tubes and cooled interior constructions of various kinds have also been utilized for the purpose of condensing a portion of the metallic vapor formed, thereby decreasing the vapor density. Another proposed solution of the above mentioned problem was the use of a heat insulated partition dividing the rectifier into a plurality of chambers which were maintained at such different temperatures as permitted condensation of the metallic vapor in one of the chambers while the vapor in the other chamber was sufficiently highly heated to be expanded so that the vapor density in the second chamber was diminished.

It has been found, however, that any interior construction will cause a voltage drop in the rectifying structure thereby decreasing the efficiency of the structure. When cooling tubes or cooled portions of interior constructions are utilized in a rectifying structure, the path of the cooling medium circulating through such constructions is generally of such length that the lower portion of the path, in direct contact with the highly heated metallic vapor, becomes so hot as to be 0. entirely inoperative for cooling or condensing purposes.

It is, therefore, among the objects of the present invention to provide an electric current rectifying structure of the metallic vapor type in which the vapor density adjacent the anodes will danger of backfiring.

Another object of the invention is to, retain the major portion of the metallic vapor in the space directly adjacent the cathode of a rectifying 69 structure thereby preventing filling up of the 5 operating space adjacent the anodes .withmetallic vapor.

A further object of the invention is to provide an electric current rectifying structure which b will prevent the'formation of such amounts of metallic vapor as would raise the vapor density adjacent the anodes to a dangerous'value; without the use of partitions or other internal structure which would cause a voltage drop through the rectifying structure. 1 Objects and advantages, other than those above set forth, will be apparent from the following de, scription and the'drawing in'which,

Figure 1 is a vertical cross-sectional view Of- 4? 15 be substantially decreased thereby reducing the electric current rectifying Structuresho' embodiment'of' the present'inventionf" Fig; Z'is'a view similar to and'sh'owing a modi fied form of the embodiment shown in Fig. 1 and,

Fig. 3 is a modified embodiment of the invention showing means arranged to reduce the voltage drop in the rectifier to a minimum value.

Referring more particularly to the drawing by characters of reference, numeral 5 indicates the main portion of a tank or container which is formed with double Walls to permit the circulation of a cooling medium therethrough and which is provided at substantially the central point of the bottom thereof with an aperture surrounded by a cylinder 6 of insulating material closed at 99 the lower end by a double-walled bottom plate 7 to form a well for receiving the liquid metallic cathode material 8. The tank 5 is closed by a cover member or top 10 having a plurality of anodes 11 extending thereth-rough and insulated therefrom.

A grid or grate 12 formed of tubing is supported adjacent the upper edge of the annular member 6 in either insulated or uninsulated re.- lation and is connected by a conduit or supply tube 13 to an exterior source of cooling medium (not shown). The grate 12 is connected at one end thereof with a connecting tube 15 joining the grate to one end of the double walled bottom plate 7. The opposite end of bottom plate 7 is 05 joined with the double walled portions of tank l 5 by a connecting tube 16. Electrical conduction through the several connecting tubes is prevented by the insertion of sections of insulating tubing thereinto. Cooling medium supplied through supply tube 13 circulates through grate 12 and is led to double Walled bottom plate 7 from which it is conducted to the double walled portions of tank 5. The cooling medium is, therefore, supplied at its lowest temperature to the grate 12 and is, thereafter supplied to bottom plate '7 from which it flows to tank 5. It will be seen that this circuit of cooling medium is such as to supply the cooling medium at its lowest temperature to the point at which the mercury vapor is to be condensed and then to conduct the cooling medium to the next most highly heated portions of the structure and, finally, to deliver the same to those portions of the rectifying structure in which the temperature differences between the structure and the cooling medium are least. The grate 12 may be formed of either electrical insulating or conducting material and when formed of electrical conducting material may be connected to an external source of either alternating or direct current in any of the well known electrical circuits whereby the grate is made to function as a control grid for the anodes. If it should be found necessary to increase the amount of cooling beyond that obtainable by a single grate, a plurality of grates may be connected in series as shown in Fig. 2.

If it is found that a grate of circular crosssection produces an objectionable voltage drop in the current rectifying structure the grate may be formed as a quadrilateral, as shown at 17, in Fig. .3. The connection of grate 17 with the source of cooling medium, the bottom plate '7 1 and the walls of the rectifier is the same as that shown in Fig. l, as will be seen by reference to the drawing.

The cooling grate is placed at the location in the rectifier at which it can be most efficiently 'used in such manner that the relatively small cathode space is cut off from the remainder of the rectifier and is the only portion of the rec tifier filled with mercury vapor. The several portions of the grate are so placed that the path of the arc is only slightly obstructed and the grate may be so shaped as to substantially prevent the occurrence of'a voltage drop.

Although only a few embodiments of the present invention have been illustrated and described, it will be understood that various other embodiments are possible, and that various changes may be made without departing from the spirit of the invention or the scope of the claims.

The invention claimed is:

1. In an electric current rectifying device, a double-walled tank having an extension, a double walled plate closing the extension and arranged to receive a liquid metal forming a cathode, anodes extending into said tank, and a tubular grate arranged adjacent the cathode, means connecting said grate with said plate, and means connecting said plate with said tank to form a path for the flow of cooling fluid serially through said grate, through said plate and thence through said double-walled portion of said tank.

2. In an electric current rectifying device, a

container having an aperture and being provided with a double-Walled portion, a receptacle closing said aperture arranged to receive a vaporizable cathode material and having a double-Walled portion, a cooling member arranged immediately adjacent said cathode material having passages therethrough forming a path for flow of a cooling medium, conduit means connecting said member with said double-walled portion of said receptacle, and conduit means connecting said double-walled portion of said receptacle with said double-walled portion of said container, the said conduit means forming paths for the flow of a cooling medium sequentially through said member, through said double-walled portion of said receptacle and thence through said double-walled portion of said container.

OSKAR SEITZ. 

